Reaction time explains IQ's association with death

Area of Science:

• Cognitive epidemiology
• Psychology
• Public Health

Background:

• Lower psychometric intelligence (IQ) is linked to increased all-cause mortality.
• The underlying mechanisms connecting IQ and mortality remain largely unknown.
• Potential confounding factors like education, social class, and smoking have been investigated.

Purpose of the Study:

• To investigate the relationship between psychometric intelligence, reaction time, and all-cause mortality.
• To determine if reaction time mediates the association between IQ and mortality.
• To underscore the significance of cognitive factors in health and survival.

Main Methods:

• A representative sample of 898 individuals aged 56 were assessed for psychometric intelligence and reaction times.
• Participants were followed up for mortality until age 70.
• Statistical analyses adjusted for potential confounders including education, occupational social class, and smoking.

Main Results:

• Both IQ and reaction time were significantly associated with all-cause mortality.
• The IQ-mortality association remained significant after adjusting for education, social class, and smoking.
• The association between IQ and mortality was no longer significant after adjusting for reaction time.

Conclusions:

• Reduced efficiency in information processing, as indicated by reaction time, may be a key factor linking lower mental ability to earlier death.
• Cognitive epidemiology provides strong evidence for the role of psychological factors in physical health and survival.
• Understanding these mechanisms could inform interventions to reduce health inequalities.